Ammonia is toxic to plants when present at elevated amount in fertilizer and composts. Ammonia in any amount is toxic to fish. In beer and wine samples, ammonia spoils the flavor qualities. Ammonia in the air is odorous and hazardous to health. In soils ammonia can be measured to help maintain nutrient balance.
The present invention relates to test kits that can be used to determine the volatile ammonia content, indicative of the chemical nitrogen stability of a selected sample. The test is especially intended for manures, feces, compost or solid organic waste and other biological samples including soil, beer pulp and water and air. The test kit comprises a first reactant mass, that exhibits a color change in the presence of varying quantities of ammonia (NH3), whereby the test kit can be used to test for the ammonia gas content in a compost sample, and indirectly the total ammonium. The test kit is especially designed for use by operators of facilities where digested sludge, leaves, manure, and other waste products, are being processed or transformed into useful compost, having value as a natural fertilizer. The test kit may also enable operators of animal facilities to determine the level of ammonia gas likely to be produced in confined quarters, since ammonia gas has a negative impact on animal health and worker safety. Ammonia determined as a volatile gas from low levels of NH3 gas in a compost sample is indicative of a state of xe2x80x9cmaturityxe2x80x9d or completion of the compost process.
Composting is a process of biological oxidation of organic materials, e.g., digested sludge, leaves, etc., whereby the materials are dewatered and deodorized into a finely divided condition, suitable for use as a fertilizer. The composting operation can be carried out by either a windrow-composting procedure, an in-vessel procedure, a back-yard bin procedure, or a static pile composting procedure.
In a composting procedure, waste products are formed into elongated or conical piles. Periodically, a composting machine is employed to rotate, to lift, mix, and shred the organic materials, so that materials near the outer surface of the windrow, exchange places with materials in the interior zone of the windrow. With compost processing of manures and other wastes, normally a period of between two (2) and twelve (12) weeks of biological activity is required to bring the materials to a stable condition at which point there is little if any residual ammonia content.
The production of ammonia gas by the breakdown of proteinaceous (high-nitrogen) materials is a normal process in all decomposition and even in fermentation processes. The evolution and evaporation of ammonia gas in composting or from waste piles is governed by the ratio of total carbon to total nitrogen (C:N ratio) in the initial compost blend. In soil the release of ammonia from urea or ammonium salt fertilizers is governed by the pH. Nitrogen is prevalent in all proteinaceous materials, such as manure, urine, fresh plant and animal materials, waste-water treatment solids (biosolids), fermentation broths and wastes, food wastes, animal feeds, etc. It is a goal of fertilizer manufacture and composting to balance the carbon, nitrogen and pH so as to limit loss as free gas vapor NH3. If nitrogen is present in excess of the needs of micro-organisms in compost or soil, the surplus will accumulate and/or evaporate in the form of ammonia gas.
The accumulation and evaporation of ammonia gas is strongly affected by the pH of the compost or other medium present. Ammonia production in compost always occurs in an aqueous (water) medium, moist bio-films on the compost particles in which the micro-organisms are active. In the presence of water, the chemical form of ammonia is described by the following equation:
NH3 +H2O less than  --- greater than  NH4++HOxe2x80x94
Increasing pH is associated with increasing HOxe2x80x94(hydroxide ion), which shifts the equilibrium to the left, increasing the proportion or concentration of NH3 (ammonia gas). Conversely a low pH is associated with low HOxe2x80x94, which shifts the equilibrium to the right, decreasing the amount of volatile ammonia gas present. Ammonia gas is very volatile and therefore tends to diffuse into the gaseous medium surrounding the compost or soil and other particles and the atmosphere above the sample in the test kit.
The significance of ammonia content in compost is different for different compost end-use applications. Ammonia gas can be quite odorous and unpleasant and is rated as an irritant. Ammonia in xe2x80x9chotxe2x80x9d or unstable manures and composts can be phytotoxic, inhibiting seed germination and causing xe2x80x9cburningxe2x80x9d or yellowing of plant foliage when applied to soil. The presence of a high NH3 gas content in the compost materials indicates that the composting process is incomplete, and that the material is biologically unstable. However, a high test result for volatile NH3 content may also indicate that a compost would be an excellent source of soluble nitrogen (ammonia) fertilizer in some applications where phytotoxicity is not expected. The present invention relates to low cost test kits, that can be used by the facility operator to determine approximately the volatile ammonia content, whereby the operator can then make an informed decision as to controlling the C:N ratio or pH of the materials to reduce ammonia levels, or otherwise changing or ending the treatment process parameters.
The primary object of the present invention is to provide test kits that can be used to determine the xe2x80x9cvolatile ammonia contentxe2x80x9d and chemical stability of a selected biological sample. The test kit comprises a first reactant mass, that exhibits a color change in the presence of varying quantities of ammonia (NH3), whereby the test kit can be used to test for the ammonia NH3 content in a compost or manure or fertilizer sample. The present invention contemplates a test kit for determining the volatile ammonia content and nitrogen-stability of a moist biological sample. The test kit comprises a small container, or jar, adapted to contain, and fully enclose, a small compost or manure or other sample, whereby NH3 gas emitted by the sample is trapped within the container. A reactant mass is supported within the container, so as to be in contact with the emitted gases, said reactant mass comprising an acidic medium that acts as a xe2x80x9csinkxe2x80x9d for ammonia, thereby drawing it out of the air, and a color change compound, responsive to pH changes in the reactant mass.
The jar is left undisturbed for a period of time, e.g., about three to four (3-4) hours, during which time NH3 gas diffuses out of the sample and into the reactant mass. The amount of ammonia gas that diffuses into the reactant mass is proportional to the ammonia gas concentration in the compost sample. Chemical reactions occurring in the reactant material are visibly recorded as a color change in the color change material. Therefore the extent of color change is proportional to the ammonia gas concentration in the sample.
In summary, and in accordance with the above discussion, the foregoing objectives are achieved in the following embodiments.
1. A test kit for determining the volatile ammonia concentration of a biological sample comprising:
a container;
said container having a transparent side wall, and an open end;
a reactant support tab;
a reactant mass carried by said reactant support tab, said reactant mass comprising an acidic pH reactant material, and a color change indicator material; and
a cover removably and sealably engaged on said open end of said container;
whereby the color of said reactant mass may be observed through said transparent side wall of said container.
2. The test kit for determining the volatile ammonia concentration of a biological sample, as described in paragraph 1, wherein said color change indicator material undergoes color changes in the pH range from about 3 to about 9, whereby said test kit can be used to test for volatile ammonia content in said container.
3. The test kit for determining the volatile ammonia concentration of a biological sample, as described in paragraph 1, wherein the said acidic pH reactant material comprises potassium-hydrogen-phthalate.
4. The test kit for determining the volatile ammonia concentration of a biological sample, as described in paragraph 1, wherein said color change indicator material comprises a first substance undergoing a color change in the pH range from about 3 to about 6, and a second substance, undergoing a color change in the pH range from about 7 to about 9, whereby said material has a range of colors from yellow to blue, depending on the pH.
5. The test kit for determining the volatile ammonia concentration of a biological sample, as described in paragraph 1, wherein said reactant support tab further comprises;
a flat blade, having a relatively shallow recess therein;
said reactant mass being located within said recess;
a handle to facilitate insertion of said tab into said container without touching said reactant mass;
whereby said blade allows for insertion into, and selfstanding within, a biological sample within said container.
6. The test kit for determining the volatile ammonia concentration of a biological sample, as described in paragraph 5 wherein said shallow recess has a depth of about two (2) millimeters; and said reactant mass, being a flat patch of material filling said recess, whereby said patch has a thickness of no more than about two (2) millimeters; the surface of said recess being etched to better adhere said reactant mass.
7. The test kit for determining the volatile ammonia concentration of a biological sample, as described in paragraph 1, wherein said reactant mass has a face area of about one (1) square inch.
8. The test kit for determining the volatile ammonia concentration of a biological sample, as described in paragraph 1, wherein said reactant support tab is inserted a biological sample so that the reactant mass is in a container space not occupied by the said biological sample and not directly in contact with said biological sample.
9. The test kit for determining the volatile ammonia concentration of a biological sample, as described in paragraph 1, wherein said reactant mass further comprises an inert carrier material; said reactant material and said color change indicator material being uniformly dispersed within said carrier material.
10. The test kit for determining the volatile ammonia concentration of a biological sample, as described in paragraph 9, wherein said carrier material is agar gel.
11. The test kit for determining the volatile ammonia concentration of a biological sample, as described in paragraph 1, wherein said biological sample is a liquid having a pH increased to 11.0.
12. A test kit for determining the volatile ammonia concentration of a surrounding environment comprising:
a container;
said container having a transparent side wall, and an open end;
a reactant support tab;
a reactant mass carried by said reactant support tab, said reactant mass comprising an acidic pH reactant material, and a color change indicator material; and
a gas permeable cover removably engaged on said open end of said container;
whereby the color of said reactant mass may be observed through said transparent side wall of said container.